(* -*- sml -*- *)

structure Tree =
struct

  (*%
   *)
  datatype 'a tree =
           (*%
            * @format(value) "L" value
            *)
           Leaf of 'a
         | (*%
            * @format(lelem left * relem right) {"N(" left(lelem) "," +1 right(relem) ")"}
            *)
           Node of 'a tree * 'a tree

end
